Bluemoon Posted November 16, 2009 Share Posted November 16, 2009 Ok I had the common problem of the overdrive not working due to the electrics, seemed like a bad connection from the pins to the plugs on the control unit, I've spread the pins a bit, and all seems ok but I've had it all unplugged and looked at before and did nothing else, and all was fine so only time will tell. I remember reading about using one or two relays to mimic the control unit, to stop it working while reversing( not sure if it does any damage), and whether the speed sensor could be incorporated. Anybody with knowledge on how to do this. cheers Brian Quote Link to comment Share on other sites More sharing options...
western Posted November 16, 2009 Share Posted November 16, 2009 the electrical control doesn't work below 30mph, that's why the speed sensor is in the circuit, it cannot work in reverse either. you can just wire the solenoid to a switch/relay leaving the speed sensor out of the circuit, then you will have manually switched control & no auto cut out below 30mph, the OD operation is then similar to the old LaycockOD that was fitted to Triumph Mk2 2500 PI & similarly fitted older cars most GKN problems are either a faulty control box/speed sensor/solenoid. I've recently lent a spare control box to a mate to cure a fault on his GKN fitted Td5 110DC. I have found if the oil level is low, the OD takes ages to disengage when selected out & tpping up the oil seems to cure it, because it's electrically selected but hydraulically operated by the solenoid. Quote Link to comment Share on other sites More sharing options...
V8 Freak Posted November 16, 2009 Share Posted November 16, 2009 Brian, I suffered a break in the wires coming from the solenoid to the control unit in the cab. Mine are routed in through the gator for the gear lever and were folded over the lip. The wires on mine are quite soft and one just broke internally. I "hotwired" one by one to prove it would work and then chopped the wires down removing the part by the lip and resoldered. I added protection in the form of some plastic tubing to protect the wires over the lip. Are you getting any flashing from the LED on the gear lever ? Or does it pretend like it's all working perfectly, but just not actually working? (Engaging the overdrive) A good person to talk to is Martin at Devon4X4. He looks after the UK warranty for GKN and knows a lot about the units. Neil Quote Link to comment Share on other sites More sharing options...
Bluemoon Posted November 17, 2009 Author Share Posted November 17, 2009 it worked perfect for a while (2 years) then would drop out of gear , then take a while to go into gear, but guessed that might be due to oil, checked and topped up, but no real difference. Quite often the telltale light would not show on startup, have to wait and see if I've fixed it. Brian Quote Link to comment Share on other sites More sharing options...
mmgemini Posted November 17, 2009 Share Posted November 17, 2009 Ah !! You mean the ELECTRONICS...... I threw my electronic control box away and fitted a new new switch because the switch on the gear lever didn't seem strong enough to take electrical current rather than the electronic current. Then I fitted a five pin change over relay to stop the overdrive being selected when going into reverse. Quote Link to comment Share on other sites More sharing options...
Bluemoon Posted November 17, 2009 Author Share Posted November 17, 2009 I think that was what I was after, could you draw up a wiring diagram and details of the relay, cheers Brian Quote Link to comment Share on other sites More sharing options...
reb78 Posted November 17, 2009 Share Posted November 17, 2009 How does the relay work Mike? (really, how does it know you are in reverse/selecting reverse?) Via the reverse light switch? Quote Link to comment Share on other sites More sharing options...
mmgemini Posted November 17, 2009 Share Posted November 17, 2009 Just now my head is ringing. I'm in the middle of a nice model that has to be finished in a week. Have a look here .... http://forum.innovate4x4.com/index.php?showtopic=312 If I remember I'll look for the wiring diagram tomorrow. I know if it's selected because I have a warning light on the gear lever. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted November 18, 2009 Share Posted November 18, 2009 Here we go No remember I did this over a year ago. I have Weetabix each morning for breakfast, I can't remember what I had for breakfast today !!! I'm just using pin numbers Alright ? 30 live from battery or ignition 85 earth 86 reverse. Well that's all is says on the note. IIRC you have to undo the reverse light connector under the cubby box and lead a wire to this terminal. Make sure that the connectors here are TIGHT, yes I had one come loose. That leaves two pins. One will be live with ing on. Use that one to the overdrive solenoin. The other should be dead. CHECK Then as you select revers the relay trips and cuts the supply off to the overdrive solenoid. My nots are not clear here but ity looks as if 87 is the live and 87a the dead one. Check with a test lamp. HTH Quote Link to comment Share on other sites More sharing options...
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